Is depressurisation the answer?
A thought. If you're hijacked perhaps depressurising and staying high is the answer. It would either kill or knockout the hijackers if they failed to put a mask on or it would imobilize them because they would need to keep a mask on. It wouldn't stop a bomb, maybe, but it's an idea. You may then be able to move about with the portable oxy bottle and "tke care " of the bandits. With a crowbar to the head.